This invention relates to increasing the impact resistance in rubber-modified vinyl aromatic polymers while reducing residence time in polymerization system.
The desirability of producing higher impact resistant vinyl aromatic polymer, such as rubber-modified styrene polymer, it is well known in the art. Compositions and methods have been developed which produce high impact polystyrene by the incorporation of a rubber-polystyrene discrete phase into a polystyrene matrix. In a plug-flow, continuous vinyl polymer manufacturing system similar to that disclosed in U.S. Pat. No. 3,945,976, incorporated herein by reference, the total residence time typically ranges from about 10 to 20 hours. A method which decreases the residence time, thereby increasing effective capacity, without sacrificing physical properties, would be important commercially. A method which actually improves physical properties would be very desirable.